Kung Fu isn't a martial art; that is a mistake of the West.  Kung Fu means "mastery of an art," roughly.  The alternate term is Wushu, meaning military skills; but, that also encompasses a lot.

Even Okinawan histories credit the development of karate to influences brought to the island by Chinese settlers, who arrived in the late 1300s, after developing relations with the Ming Dynasty  Chinse Shaolin Boxing (a catch-all for Shaolin Temple-derived techniques) were taught to upper classes who studied in China and forms were taught to others, in cultural exchanges.  With the ever growing restrictions on weapons authorized for the lower classes, empty-handed fighting techniques grew and spread, as did adapting thing like farming tools to weapons (sickles became kamas, stick weapons, like nunchaku and tonfa, etc).  So, it is not a stretch that a Chinese master would teach Diana techniques that were akin to karate techniques, especially things like White Crane and Wing Chun.

Bruce Lee's base style was wing chun, which was developed by a Buddhist nun, named Wing Chung.  It was taught to other women, to protect themselves against bandits and rapists, with specialization in close-quarters fighting.  Lee learned from Yip Man, and then began to incorporate other techniques, as he sparred and worked out with others, plus things like footwork, from boxing and his own love of dancing.  He learned groundfighting techniques from Gene LeBell, who was a champion American judoka, stuntman, and pro wrestler (his family promoted wrestling and boxing at the Olympic Auditorium, in Los Angeles, until the early 80s) and Filipino techniques from Dan Inosanto, while sharing his own techniques with them and others.

Denny O'Neil had more than a little knowledge about the martial arts; but, these things tended to spread as fads and often you got incorrect info because of lazy Hollywood writing or bad journalism, or just a frame of reference.  Judo spread through the world in the 20s and 30s, but movies would refer to "judo chops," when that isn't a part of judo.  They didn't know the difference between karate and judo.  Karate became better known in the post-WW2 era and into the 1960s.  Chinese wushu/kung fu became better known in the 1970s, then tae kwon do and other forms of kickboxing, in the 80s.  Savate had been around since the 1800s, formally (it grew out of streetfighting techniques of French sailors, who learned things like muay thai kickboxing and Persian wrestling, and brought them back to Marseilles), and any kind of kick fighting, for generations, was called savate, before karate and other arts became known.

James Cagney studied judo and worked it into a couple of films, like Blood on the Sun.....




Bad Day At Black Rock features an early depiction of karate, as mentioned above.....



Ian Fleming had also written of karate in Goldfinger, in discussing Oddjob.  Bond is said to have trained in judo, at university and the military.

During WW2, commandos and other special units, like the OSS, were taught streetfighting techniques, by William Fairbairn, a former Shanghai police officer, with extensive background in streetfighting in that violent city.  He developed what he called Defndu, which was a basic, no holds barred, gutter fighting, using various effective techniques to disable, cripple, and even kill an enemy.  They involve attacks to vulnerable areas, like the solar plexus, the collar bone, knees and elbows, the throat, the eyes, under the jaw, the nose, kidneys and other areas.  Krav Maga, the Israeli combat art, developed from those teachings.

The 1960s war film, The Devil's Brigade, about the 1st Special Service Force (one of the precursors to the Green Berets) featured a demonstration of fairly credible techniques taught by Fairbarin and his hand-to-hand instructors.  It gets a bit exaggerated at the end, but is relatively faithful, at the start....





In the 70s, the Billy Jack films popularized hapkido, a Korean style, used by the fight coordinator and Tom Laughlin's stunt double, Bong Soo Han....



Bruce Lee and Shaw Bros kung fu films popularized Chinese martial arts in the 70s, with the tv series Kung Fu being the biggest influence, outside Lee.  David Chow, the fight choreographer, filled it with several Chinese styles, as well as other martial arts, including catch wrestling, as seen in an episode when Caine fights two American wrestlers, with one played by Gene LeBell.  Here, David Carradine, as Caine, faces another Shaolin, a bounty hunter, played by fight coordinator David Chow......



The Karate Kid brought a resurgence in interest in karate styles,  while Chuck Norris' rise in popularity highlighted his tang soo do style of karate (Korean style) and tae kwon do would emerge as another Korean base for kickboxing.  The 90s brought Mixed Martial Arts, with the popularity of the Ultimate Fighting Championship.  MMA is pretty much the philosophy of what Bruce Lee taught, of using whatever works best, for the situation and the fighter.  In the MMA fighting world, catch wrestling combined with Brazilian jiu jitsu, which was contested in open rules fighting, in vale tudo matches, with the cage added for both spectacle (John Milius, director of Conan the Barbarian, suggested the idea, based on the pit fighting sequence, in the film), and the parcticality of containing the fight, with a boxing or wrestling ring considered dangerous, if they went through the ropes, during takedown attempts.